Description (CNA)
A flaw was found in Keycloak. An authenticated user with low privileges can exploit this vulnerability by sending an oversized subject_token JSON Web Token (JWT) to the TokenEndpoint. When the token exceeds a 4000-character limit, it is silently dropped, causing the system to fall back to client credentials. This allows the user to gain the permissions of the client's service account, leading to privilege escalation.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Red Hat / Red Hat build of Keycloak 26.4 | unaffected 26.4.13-1 before * |
| Red Hat / Red Hat build of Keycloak 26.4 | unaffected 26.4-19 before * |
| Red Hat / Red Hat build of Keycloak 26.4 | unaffected 26.4-19 before * |
| Red Hat / Red Hat build of Keycloak 26.4.13 | unaffected |
| Red Hat / Red Hat build of Keycloak 26.6 | unaffected 26.6.3-3 before * |
| Red Hat / Red Hat build of Keycloak 26.6 | unaffected 26.6-6 before * |
| Red Hat / Red Hat build of Keycloak 26.6 | unaffected 26.6-6 before * |
| Red Hat / Red Hat build of Keycloak 26.6.3 | unaffected |
CWE
CWE-1284
References
- https://access.redhat.com/errata/RHSA-2026:25097
- https://access.redhat.com/errata/RHSA-2026:25098
- https://access.redhat.com/errata/RHSA-2026:30049
- https://access.redhat.com/errata/RHSA-2026:30050
- https://access.redhat.com/security/cve/CVE-2026-9704
- https://bugzilla.redhat.com/show_bug.cgi?id=2481877
ADP enrichment
No English description supplied.
No references supplied.